> ...the UK Copyright Act explicitly states:
>
> (4) Where in any proceedings the question arises whether an article is an
> infringing copy and it is shown-
>
> (a) that the article is a copy of the work, and
>
> (b) that copyright subsists in the work or has subsisted at any time,
> it shall be presumed until the contrary is proved that the article was made
> at a time when copyright subsisted in the work....

End of story. In the case of the public self-archiving of the
unrefereed preprint prior to transfer of copyright, the contrary is
indeed proved, an infinite number of times, in perpetuo.

> ........
> (6) In this Part "infringing copy" includes a copy falling to be treated as
> an infringing copy by virtue of any of the following provisions-
> ......
> section 56(2) (further copies, adaptations, &c. of work in electronic form
> retained on transfer of principal copy),.....

On the internet, in the specific, anomalous, minoritarian case in
question (let us focus on it, to keep the issue from getting blurred),
the "further copies" are in reality "prior copies," because the cat has
been let irretrievably out of the bag (the Pandora's box has been
opened, the text has seeped into the aether) by public self-archiving
PRIOR to transfer of copyright.

How was this possible? Because in this one anomalous special case (most of
the literature is NOT an author give-away), the text's author can and
does elect to make it possible. (No sane author would do this with a
potential best-seller!

A little reflection will remind us that copyright law was never
conceived or intended for this anomalous, nonrepresentative minority
consisting of give-away texts. It was conceived and intended for the
the majority, non-give-away texts, those for which their authors (in
collaboration with their publishers) wish to make MONEY (through
royalties, fees or salary) in exchange for the product:

> My point is: publishers do not need to own exclusive rights in
> (scientific/scholarly) publications, if the author promises not to
> commercially exploit his work otherwise.

Yes, transfering copyright nonexclusively (i.e. retaining the online
giveaway rights for the author) will indeed solve the minor problem of
the legal status of the final ("value-added") refereed postprint; but,
it is for those cases where the publisher may be disinclined to agree
to nonexclusivity that the Pre-Archived Preprint Gambit was designed,
and it covers all cases: